Until recently, the echocardiography evaluation of left ventricular volume and systolic function has been performed by M-mode derived left ventricular end-diastolic and systolic dimension measurements. M-mode echocardiography more clearly identifies the endocardial surface of the left ventricle as compared with two-dimensional echocardiography. When recorded simultaneously with an electrocardiogram and a phonocardiogram, the timing of end-diastole and systole is easily recognized. Using this method of measurement, the left ventricular shape is assumed to be an ellipsoid and the ratio between the short and long axis dimension (D and L) is also assumed to be 1:2 through all cardiac cycles. This assumption has been justified by Pombo et al. and Popp et al in the absence of left ventricular deformity or wall motion abnormalities. The assumption is that the left ventricular volume =4/3 × π × L/2 × (D/2)2 = π/6LD = π/6 × 2D × D2 = π/3D2 = D3 (Pombo’s method). In cases with enlarged left ventricle, the shape of the left ventricle becomes more oval and the ratio of the long and short axis dimensions approaches 1. Therefore, the volume measurements by Pombo’s method would be overestimated in this situation. To correct this error, Teichholz et al. reported that the left ventricular volume is 7.0/(2.4+D)×D3. Furthermore, to correct the changes in the ratio of long and short axis dimension between end-systole and diastole, Gibson et al reported that the long axis dimension in end-systole is 4.18+1.I4Ds and in end-diastole 5.90+0.98Dd on the basis of cineangiography measurements. However, these M-mode derived methods may sometimes be inadequate, since deformity of shape due to HOCM or segmental wall motion abnormalities in patients with ischemic heart disease can introduce significant errors in volume measurements.